After an abrupt shutdown many settings were messed up:

• #1 Firefox was a mess. Bookmarks were gone, and I couldn't even add new ones. I had to reset firefox from safe mode and install all my addons and configure everything. This was a pain but is now solved.
• #2 The background in the login screen shows the one I chose with Ubuntu Tweak for a second, and then it puts back the default one. I tried changing it again with Ubuntu Tweak but it's still happening.
• #3 All my shortcuts in the sidebar were replaced by the default ones. I re-added them manually, also a pain.

So how can I solve 2?

And in case this happens again, is there a way to fix everything easy and fast?